The invention relates to an apparatus for measuring the viscosity or consistency of fluids, such as liquids, emulsions and suspensions.
In open containers the measuring of viscosity or consistency usually does not involve problems. According to one known method a rotating or oscillating first element and a second element mounted on a shaft which is rotatable from a predetermined position against a biasing torque are so placed in the fluid that a viscous coupling is established between them through the liquid, and the torque thereby transmitted to the second element is measured. An example of such a method is known from the U.K. patent specification No. 970,293.
If using a similar method for the measuring of viscosity or consistency of fluids in closed containers, the difficulty arises that either the measurement of torque will include the friction in a stuffing box, which may give rise to considerable errors, or some special means such as a diaphragm or bellows system must be used for transmitting the measurement of the torque from the second element out of the container. By the use of such systems the measurement may be subjected to the influence of pressure and temperature. Besides, for carrying out the measuring according to such a system relatively complicated equipment will frequently be required.